1. Field of the Disclosure
The present application relates to a liquid crystal display device, and more particularly to a liquid crystal display device adapted to improve the characteristics of gate drive voltages applied to gate lines.
2. Description of the Related Art
In an electrical information display device field, existing cathode ray tubes (CRTs) are being replaced with flat panel display devices. The flat panel display devices include liquid crystal display (LCD) devices, plasma display panels (PDPs), field emission display (FFD) devices, organic light-emitting display (OLED) devices and so on. Among the display devices, the LCD devices are being mainly used at present because of having features such as mass production technologies, an easy driver, high picture quality and a large-sized screen.
In the LCD devices, an active matrix LCD device using thin film transistors as switch elements is suitable to display moving images. In order to control the above-mentioned thin film transistor to be turned-on/off, an ordinary LCD device includes a gate driver configured to generate and apply scan signals. Also, the ordinary LCD device further includes a data driver configured to provide data signals which are used to display gray levels of an image.
FIG. 1 is a block diagram schematically showing the configuration of an LCD device according to the related art.
As shown in FIG. 1, the related art LCD device 10 includes an LCD panel 1 displaying images and drivers 4 and 5.
The LCD panel 1 includes a plurality of gate lines GL and a plurality of data lines DL which cross each other and are formed on a glass substrate. A plurality of pixels arranged in a matrix shape are defined by the gate lines GL and the data lines DL crossing each other. An image is displayed on the LCD panel 1 by data signals applied to the pixels. Such an LCD panel 1 is defined a display area A/A, in which the pixels used to display an image are formed, and a non-display area N/A surrounding the display area A/A.
The drivers 4 and 5 include a gate driver 4 and a data driver 5. The gate driver 4 replies to gate control signals GCS applied from a timing controller (not shown) and controls switch elements of the pixels arranged on the LCD panel 1 to be turned-on/off. In detail, the gate driver 4 applies gate drive voltages VG to the LCD panel 1 via the gate lines GL and enables the switch elements of the pixels to be sequentially turned-on in a single line. As such, the pixels receive data signals which are applied from the data driver 5 in every horizontal synchronous period.
The data driver 5 replies to data control signals DCS applied from the timing controller and converts digital image data into analog data signals. A single line of data signals are simultaneously applied from the data driver 5 to the LCD panel via the data lines DL in every horizontal synchronous period. In accordance therewith, the pixels display the gray levels of an image.
In such configuration of the LCD device 10, the gate driver 4 has a feature that its configuration is relatively simpler compared to the data driver 5. Also, the LCD device has been required to reduce weight, volume and manufacturing costs. In view of these points, a gate-in-panel (GIP) gate driver has been proposed. The GIP gate driver is formed on the non-display area of the LCD together with the thin film transistors on the display area A/A at the manufacture of an array substrate of the LCD panel, unlike an ordinary gate driver which is manufactured in a separate IC (Integrated Circuit) chip from the LCD panel and bonded to the LCD panel.
Meanwhile, the LCD device causes motion blur phenomena due to a critical response speed of liquid crystal. Due to this, image quality of the LCD device must deteriorate. To address this matter, an LCD device is proposed which is driven in a higher frequency mode of above 120 Hz compared to 60 Hz. If the LCD device is driven in a high frequency range of above 120 Hz, a single horizontal synchronous cycle (or period) must be shortened. As such, it is difficult to secure the turning-on time of a switch element within each pixel.
To this end, the recent LCD device enables not only a gate driver 4 to include first and second gate drivers 4a and 4b which are disposed on left and right edges of an LCD panel in a GIP mode, but also gate lines to be pre-charged by providing an overlap interval between gate drive voltages on the gate lines. As such, the switch element within each pixel can be stably turned-on.
However, although the overlay interval is provided between the gate drive voltages on the gate lines or the driving frequency becomes higher, it is difficult to increase a discharge speed of the gate drive voltage charged in each gate line is being